South African researchers discover rare alkaloids in Cannabis leaves

We already knew about Cannabis alkaloids. Researchers from’Stellenbosch University (SU) in South Africa have identified a rare class of phenolic compounds, called flavoalkaloids, in the Cannabis leaves,  a first in the scientific literature. This discovery, published in the Journal of Chromatography A, sheds new light on the chemical complexity of the plant and its potential for biomedical research beyond cannabinoids.

Headed by Dr Magriet Muller, an analytical chemist at Stellenbosch University's Analytical Centre, the team analyzed three commercial varieties of Cannabis grown in South Africa, a Cape Cookie, a CBG and a Blue Sky, from producer Cannsun Medicinals.

Using advanced two-dimensional liquid chromatography techniques and mass spectrometry they identified 79 phenolic compounds, 25 of which had never before been reported in Cannabis. Of these, 16 were tentatively identified as flavoalkaloids, mainly concentrated in the leaves of a single variety, Blue Sky.

A rare family of compounds

Phenolic compounds such as flavonoids are well known in the pharmaceutical world for their properties antioxidants, anti-inflammatories and anti-carcinogenic. However, the flavoalkaloids are exceptionally rare in nature.

«Most plants contain highly complex mixtures of phenolic compounds, and while flavonoids are widespread in the plant kingdom, flavoalkaloids are very rare in nature,» explains Dr. Muller.

The researchers did not expect to find such a large variability in phenolic profiles between just three varieties, nor to discover so many previously unlisted compounds.

«We know that Cannabis is extremely complex, it contains over 750 metabolites, but we didn't expect such variation... especially as the first evidence of flavoalkaloids in Cannabis was very exciting,» said Muller.

The analysis also confirmed that Cannabis leaves, often considered as waste in commercial production, have a very special uniquely rich chemical composition of non-cannabinoids. These discoveries could open up new prospects for their use in pharmaceutical industries and cosmetics, where phenolic extracts are already appreciated for their biological properties.

High-resolution chemistry behind the discovery

To discover these new molecules, the SU team used a state-of-the-art chromatography known as HILIC × RP-LC-UV-HR-MS. This two-dimensional approach enables extremely fine separation of compounds that would otherwise overlap in a standard analysis.

According to the Professor André de Villiers, Muller's thesis supervisor and co-author of the study, «the excellent performance of two-dimensional liquid chromatography enabled us to separate flavoalkaloids from the much more abundant flavonoids, allowing us to detect these rare compounds in Cannabis for the first time».

This method, previously applied to rooibos tea, grapes and wine, has proved remarkably effective for characterizing polar phenolic compounds of Cannabis. The research revealed significant differences between the three varieties tested, each presenting distinct phenolic profiles. One was richer in C-glycosylated flavones such as orientin and vitexin, while another showed higher levels of di-glycoside derivatives of acetin.

Broadening the scope of cannabis research

While most scientific efforts have historically focused on the cannabinoids, in particular the THC and the CBD, this study shows that other classes of compounds can have a significant significant therapeutic value.

«Our analysis once again highlights the medicinal potential of cannabis plant material, currently considered waste,» said Professor de Villiers. «Cannabis presents a rich and unique non-cannabinoid phenolic profile, which could be relevant from a biomedical research point of view.»

The flavoalkaloids, which are still only partially characterized, now represent a new frontier for scientists seeking to understand the full potential of molecules derived from Cannabis.